We are proposing the establishment of a Core Analytical Laboratory, which will perform assays in support of the multiple research projects that will be carried out under the auspices of the proposed TTURC. The advantages of a single core laboratory include the ability to make specialized assays and related consultation available on site to multiple investigators, and the flexibility and expertise to establish new assays as the interests and priorities of the center evolve in concern with new knowledge and changes in the state of the art. Uniform methodology and quality control will enhance transdisciplinary collaborations by facilitating the pooling and comparison of laboratory data across projects. Amongst the assays to be initially offered by the core laboratory are plasma cotinine as a marker of tobacco/nicotine exposure, treatment drugs and/or their metabolites, and selected hormones and monoamine neurotransmitters. Plasma cotinine will be measured to characterize subjects smoking history during recruitment, as one outcome measure during treatment studies, and to document abstinence for studies whose design requires a defined period of smoking cessation. Drugs used in treatment trials will be monitored in plasma (naltrexone/beta-naltrexol) to examine possible relationships between plasma concentrations and outcome and/or side effects. Urinary catecholamines and plasma cortisol will be measured in conjunction with studies of abstinence, and sex hormones assayed to support projects initiated by another core concerned with sex specific factors in smoking.